396 



GROWTH FACTORS AND FLOWERING 



AXILLARIES OFF 



CONTROLS ■gl 



AVERAGE DAYS TO FLOWERING 



20 40 60 80 



— I r 



T 



100 



LEAF POSITION 



Fig. 2. Effect of axillary excision on plants ready to flower at start. 

 The lack of effect on flowering is shown above; the compensatory growth 

 effect is shown below (leaf length after 28 days). 



Indoleacetic Acid (lAA) Substituted for the Axillaries 



To see if the two effects of axillary excision were a result of remov- 

 ing the axillaries as auxin sources, 1 % lAA in lanolin was placed on 

 the axillary stumps in one set of plants, plain lanolin on the stumps in 

 another set. In the hope of increasing the precision of the experiments 

 over those reported in the earher paper, particular care was taken to 

 match the sets of plants as exactly as possible. Results of a typical ex- 

 periment starting with small plants are shown in Fig. 3 and Table II. 

 It is clear that auxin substituted for the axillaries has absolutely no 

 effect on the compensatory growth caused by axillary excision; how- 

 ever, at the same time it does cause slower flowering. These results 

 were confirmed in two repetitions of this experiment (see Fig. 5 also). 

 When large plants (of ready-to-flower size) were used in three experi- 

 ments, otherwise comparable to the above, the auxin again had no 

 effect on the compensatory growth (Fig. 4), but also had no effect on 



